Combustible composition



United rates Patent 2,969,418 Patented Oct. 20, 1959 COMBUSTIBLE COP/POSITION N Drawing. Application February 8, 1957 Serial No. 638,925

Claims. (Cl. 52-2) The present invention relates generally tocombustible or burning ty'pe compositions. More particularly it relatesto compositions of this type which are oxygensufiicient and which may beused in places in which black powder and other gaseous or thermit typepowders have'been used in the past, for example, in safety or blastingfuses, military fuses, delay elements for blasting caps, tracer andflare charges, igniting cord for the transmission'of flame or fire fromone point to another, fireworks and the like. By oxygen-sufficient ismeant that the compositions of the present invention burn without theaddition of any atmospheric oxygen.

Black powder, which is a mixture of charcoal, sodium or potassiumnitrate and sulphur, has been used for many years as the burningcomposition in fuses and the like. Although satisfactory for manypurposes, black powder has an inherent disadvantage which relates to thecharcoal ingredient, i.e. it is variable in its nature and therefore theentire black powder composition is correspondingly variable in itscharacteristics and not always predictable as to rate of burning, thevolume of gaseous products evolved, the temperature of combustion, etc.Since it is essential in certain of the uses above enumerated that therate of burning and/ or the amount of gas evolved shall be definitelypredictable and determinate, black powder has therefore provedinadequate in supplying the needs of the art. In addition, black powderis susceptible to the humidity of its surroundings, readily taking upmoisture with a consequent impairinent of its efficiency. Also, blackpowder has a tendency to change on aging in certain characteristics,such as burning rate.

A principal object of the present invention is to provide a burningcomposition which may be used in general as a substitute for blackpowder and/or for other uses hereinabove enumerated and which may berelatively unaffected by the various conditions which deleteriouslyaffect black powder such, for example, as humidity and aging and whichshall be predictable in its characteristics within relatively narrowlimits. The compositions of the present invention are readilyduplicable, which is a characteristic not shared by black powder.

7 It is noted in this connection that the charcoal ingredient in blackpowder is made by the carbonization of wood, which is a highly variablenatural occurrin product. There are many different conditions ofcarbonization and many kinds of wood; wood from diiferent portions ofthe same tree may have essentially diverse characteristics when madeinto charcoal. In addition to this, the charcoal made from naturallyoccurring wood is highly porous and hence subject to being afiected byhumidity conditions; it is often more or less .adsorptive and hence issubject to variation by reason of the different amounts of differenttypes of gases which may be adsorbed on the surface of the charcoalparticles. By contrast to this, the compositions of the presentinvention utilize a uniform and substantially non-adsorptive u beprovided. It is believed, however, that such a comor inactive surfaceform of carbon as hereinafter more particularly set forth, so that thepresent compositions are uniform in their characteristics in use.

A further principal object of the present invention is to providecombustible or burning compositions in which the burning time may beadjusted within reasonable limits by adjustment of the proportions ofvarious essential ingredients of the compositions; and more particularlyin which the amount of gaseous products evolved upon burning may bevaried and controlled within reasonable limits, exclusive of the burningtime. So far as is known, the compositions of the present invention arethe first ones wherein this dual adjustment of burning time and theproportionate amounts of gaseous products of combustion areindependently adjustable.

Summarizing the present invention, it comprises a composition includingas oxidizing agents 1) a nongas-producing alkaline earth peroxide (BaOwhich is present to the extent of about 65% to and (2) a gas-producingalkali metal nitrate (KNO which is present to the extent of about 4% to25%; and as fuels a non-gas-producing material such as metallic siliconwhich is present to the extent of about 1% to 10%, and a gas-producingmaterial consisting of one or more particular types of carbon blackspresent to the extent of about 1 to 15%. In addition to this, in' someof the more highly refined embodiments of the invention, there may beadded a binder which is a combustible organic plastic material, such asnitrocellulose and which is present to the extent of about 3% to 10% ofthe entire composition. Furthermore, in a particular preferredcomposition there may be added a desensitizingmaterial comprising ametallic stearate, such as aluminum or zinc stearate, which may bepresent to the extent of about 0.1% to about 1.0%. It is within theintended scope of this invention that minor amounts of other ingredientsmay be added to improve the compositions in various minor respects.

The materials aforesaid, with the exception of the organic plasticbinder, are preferably dry-mixed and blended together and then admixedwith a volatile solvent-solution of the organic plastic binder (lacquer)to form a slurry, which may then be cast into thin sheets. After thesolvent has evaporated therefrom, the cakes are broken down, grained,sieved to select a desired particle size, and the particles coated withgraphite to improve their moisture-resistance and flow characteristics.

The details of the present invention will appear hereinafter from aparticular discussion of the several ingredients, their characteristicsand their equivalents, and also a discussion of the eifects to beattained by varying the proportions of difierent ingredients.

vConsidering now the characteristics of the several essentialingredients, there are in this composition, as in most mechanicalmixture types of burning compositions, one or more oxidizing agents andone or more fuels. In this case there is a non-gasproducing and agasproducing oxidizer and a non-gas-producing and a gasproducing reduceror fuel.

' In the class of oxidizing agents, the first element which is presentto the extent of 65 to 90% of the weight.

of the active ingredients of the composition is a low gas producingalkaline earth peroxide such as barium peroxide (BaOg). Theweight'proportions given in the examples hereinafter given applyparticularly to barium peroxide.

As a non-gas-producing fuel, the present invention utilizes metallicsilicon.

It is recognized that if barium peroxide and silicon were mixed, with noother materials present, a non-gasproducing burning composition of thethermit type would position would not fulfill all the requirements inthe present case, as it would not provide for the evolution of any gas,some of which is needed, for example, in connection with fuse powders toprovide an end-spit," that is, an evolution of highly heated gaseousproducts of combustion and/or sparks or flames as required to ignite acharge at the termination of the burning of a length of fuse. 7

According to the present invention there is also pro vided a high oxygenproducing alkali metal nitrate, such potassium nitrate. This material,when reacted, furnishes a readily available supply of oxygen andprovides ad- 'ditional gaseous products such as nitrogen or some oxidethereof.

In addition, there is present according to the invention a gas-producingtype of fuel, namely carbon black, but only in one or more of certainselected and particular types. Carbon black usable in the presentcompositions may be generally of three groups consisting of (a) furnaceblack and thermal furnace blacks, (b) acetylene blacks and (c) syntheticgraphites. Processes for making the various forms of carbon aforesaidare described in the book Industrial Carbon by C. L. Mantell (publishedby D. Van Nostrand Company, Inc., of New York city in 1946).

The preferred carbon blacks, known as furnace and thermal furnaceblacks, respectively, are those charac terized by having low adsorptivecapacity or surface activity. Channel blacks are not acceptableaccording to the present invention.

Satisfactory forms of carbon or blacks for the purposes of thisinvention have properties as listed below:

Average particle size 40 to 500 rnillimicrons. Fixed carbon content 98%(minimum). Volatile content 2% (maximum). Hydrogen ion values Diphenylguanidine adsorption 7-11.

value 10 (maximum). Oil adsorption value 40 to 90.

These values are obtained by methods familiar to the carbon and pigmentindustries and described in the book above referred to.

If the composition were made up, for example, with nothing but bariumperoxide and silicon, there would be little or no gas evolution onburning; whereas if the composition were solely potassium nitrate andcarbon, there would be considerable gaseous evolution upon burning. Thepreferred compositions are somewhere between these two extremes and inpractice are such that the products of combustion will be about 10% to18% (by weight) gaseous and the balance solid. The higher limits of thisrange of variation are attained by proportionately increasing thecontent of the gas-producing ingredients and correspondingly reducingthe proportions of non-gas-producing ingredients, both as above defined.

The next variable to be particularly considered is the speed of burning.This is important when the com burning rate powders over a fairly widerange of barium peroxide content, thus varying the amount of gasproduced. When the proportions of carbon and silicon are 4 l relativelyhigh, the speed of combustion is relatively faster; when these fuels arereduced, the speed of combustion is slowed. Replacing a part of thesilicon with carbon increases the amount of gas and vice verse. As tothe nitrate, increased proportions of this ingredient result inprogressively slower burning rates and higher amounts of gas and viceversa.

Another possible control of burning rate is in the particle size of thecarbon used, finer particles of carbon in general producing fasterburning power. When graphite is used as the carbon ingredient, a slowerburning powder is produced than with other types of carbon black whichare usable in accordance with the definition given above. Thus, afurther way to provide a relatively slower burning powder is to replacea certain amount of the carbon black with graphite.

Another way to control the speed of burning of compositions according tothis invention is to select a type of carbon within the limits abovegiven, but with different adsorptive characteristics, those types havinghigher adsorption characteristics, as measured by higher diphenylguanidine values, producing faster burning powders.

In general, the powders or compositions according to the presentinvention provide relatively less gas evolution per unit of weight thana corresponding weight of black powder. The calorific values of theburning compositions of the present invention may be relatively lowerthan those of black powder, but they usually burn at highertemperatures, which is very desirable for certain uses.

For ease in handling and use, it is desired that the compositions, whichare basically in accordance with the present invention, shall befabricated in a form of a grained powder. In order to produce acommercially usable powder in grained form, it is desired to mix thepowder ingredients in finely divided form mesh and smaller) with abinder material which comprises a combustible organic plastic insolublein water, but soluble in conventional aliphatic organic solvents i.e. alacquer. The preferred binder in accordance with the present invention.is a nitrocellulose (soluble in esters and ketones) having a nitrogencontent of about 12% and a viscosity in the range of about 60 toseconds. If it be considered that the four essential ingredients shallbe present in the proportions aforesaid so as to make up collectively100 parts by Weight, then there should be added from about 3 to about 10parts by weight of nitrocellulose in the form of a lacquer. Once thenitrocellulose lacquer slurry is dried, the process of making the powderas described above is substantially the same as known processes ofpreparing grained black powders. The process of this invention, however,effectively eliminates the cumbersome wheel mills and presses which havebeen conventionally used in black powder manufacture and at the sametime produces a combustible material having a high density by reason ofthe effective displacement by the liquid binder of air from theinterstices between the particles making up the composition, followed bycareful vaporization of the solvent so as to leave the cake insubstantially unchanged condition.

In some instances it may be desired to use additional ingredients in thecomposition prior to the making up. of the slurry as aforesaid, theseingredients being, for instance, for decreasing the moisture and Watersusceptibility of the composition, decreasing the sensitivity of thecomposition to impact, friction or spark or, perhaps, raising theignition temperature of the composition.

Such an added material may be a metallic stearateg" such as aluminumstearate and zinc stearate, and may be present in the final compositionin an amount varying from about 0.1 to 1.0 part by weight based upon100- such parts for the four essential ingredients as aforesaid. Thecompositions of the present invention may be further illustrated byexamples of compositions embodying this invention as follows:

Example 1 The active ranges of ingredients of preferred compositionsaccording to the present invention may be listed as follows:

. Percent Barium peroxide 65-90 Potassium nitrate 4-25 Silicon 1-10Carbon black (as herein defined) 1-15 Example 2 Examples of relativelyslow burning powders consisting essentially of the four activeingredients above defined are in the following ranges:

Example 3 Compositions having medium burning rates would be found in thefollowing ranges of ingredients:

Ingredient: Compositions, percent Ba a 70-86 KNO 5-21 Si 7 3-6 C (asherein defined) 3-6 Example 4 Compositions having relatively fastburning rates are as follows:

Example 5 An example of a grained powder, including not only the fouressential ingredients hereinabove given, but also the nitrocellulosebinder and aluminum stearate, and which may be considered as one of thepreferred embodiments of the invention is as follows:

Percent Barium peroxide 79.5 Potassium nitrate 5.6 Silicon 5.6 Carbon(as herein defined) 2.8 Nitrocellulose 6.0 Aluminum stearate 0.5

In the foregoing disclosure there are set out the essential ingredientsof compositions according to the present invention, the proportions inwhich these ingredients may be present in the composition as a whole,and the effects of. changing the proportions within the limits given toattain certain specific and desired results.

It is intended that the scope of this invention shall be measured by theappended claims, which are to be construed validly as broadly as thestate of the prior art permits.

What is claimed is:

1. An oxygen-sufficient combustible composition for use in safety fusesand the like and which provides independent adjustability of the burningtime and of the amount of gases evolved, said composition comprising thefollowing ingredients in the weight proportion stated:

Percent BaO 65-90 KNO 4-25 Si 1-10 Carbon (as defined) 1-15 all saidingredients being present in a particle size of not larger than about(Tyler) mesh; said carbon being selected from the group consisting of(a) furnace blacks and thermal furnace blacks, (b) acetylene blacks and(c) synthetic graphites, said carbon further having the followingproperties:

Average particles size 40 to 500 millimicrons. Fixed carbon content 98%(minimum). Volatile content 2% (maximum). Hydrogen ion values 7-11.Diphenyl guanidine adsorption value 10 (maximum). Oil adsorption value40 to 90.

2. An oxygen-sufiicient combustible composition in accordance with claim1, comprising in addition a metallic stearate selected from the groupconsisting of aluminum and zinc stearates and serving as a desentitizerand present in an amount of about 0.1 to about 1.0 part by weight per100 parts of the total materials recited in claim 1.

3. An oxygen-sufiicient combustible composition in accordance with claim1, comprising in addition a binder which is present in an amount ofabout 3% to about 10% by Weight per 100 parts by weight of the total ofmaterials recited in claim 1.

4. An oxygen-sufiicient combustible composition in accordance with claim1, comprising in addition nitrocellulose serving as a binder which ispresent in an amount of about 3% to about 10% by weight per 100 parts byweight of the total of materials recited in claim 1.

5. An oxygen-sufficient combustible composition in accordance with claim1, which is present in the form of a grained powder and which consistsessentially of the UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No. 2,909,418 October 20, 195% David Ea Pearsall It is herebycertified that error appears in the -"printed specification of the abovenumbered patent requiring correction and that the said Letters Patentshould reed as corrected below.

Column 3, line 11, before. "potassium" insert we as 5 lines 39 and 40should appear as shown below instead of as in the patent:

'- ion val e seasoned Willa P .g anidine adsorption ii;

\A; g I column 4, line 4, for "vice; Verse" read' vice versa line 1G,for "power" read powder column 6, line 19, "particles" read particle vSigned/and sealed this Brd daY d 1960 XSEAL) ttest:

KARL V v ROBERT c. WATSON Attesting Officer I "l I v I Commissioner ofPatents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.2,909,418 Getober 20, 1959 David E. Pearsall It is hereby certified thaterror appears in the printed specification of the above numbered patentrequiring correction and that the said Letters Patent should reed ascorreqted below.

Column .3, line 11, before: "potassiim" insert the as lines 39 and. 40should appear es shown below instead of as in the patent:

flydmen i onvalues e 7=ll@ Diphenyl guanidine adsorption v col mn 4,-lin 4, for "vice: Yer'S'e read vice verse line 18, for "power" readpowder column 6 line 19, "particles" read particle Si ned'eha sealedthis g A'da zdf-my 1960.,

' SEAL) ttest:

, ROBERT (J. WATSON Attesting Officer Commissioner of Patents

1. AN OXYGEN-SUFFICIENT COMBUSTIBLE COMPOSITION FOR USE IN SAFETY FUSESAND THE LIKE AND WHICH PROVIDES INDEPENDENT ADJUSTABILITY OF THE BURNINGTIME AND OF THE AMOUNT OF GASES ENVOLVED, SAID COMPOSITION COMPRISINGTHE FOLLOWING INGREDIENTS IN THE WEIGHT PROPORTION STATED;